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Nov. 28, 2012 -- For many people with Parkinson's disease, depression affects quality of life more than the symptoms such as shaking, according to new research.

"At least 50% of people with Parkinson's have depression," says Michael S. Okun, MD, national medical director of the National Parkinson Foundation and professor of neurology at the Center for Movement Disorders at the University of Florida, Gainesville.

That was a main finding of the Parkinson's Outcomes Project, a report released today by the National Parkinson Foundation.

"The big news is how large of a role depression plays in Parkinson's disease, how under-diagnosed and under-treated it is," says Joyce Oberdorf, CEO and president of the foundation.

The impact of depression on the health of people with Parkinson's is nearly twice that of movement problems, the researchers found.

About 1 million people in the U.S. and more than 4 million worldwide have the disease. It is marked by tremors and difficulty with walking, movement, and coordination.

Tracking Parkinson's Patients

Beginning in 2009, the researchers evaluated the care of more than 5,500 patients, ages 25 to 95. They went to 20 Centers of Excellence in the U.S., Canada, Israel, and the Netherlands.

About 9,000 clinic visits were included.

The researchers looked at information about medications, referrals to specialists, and rates of depression and anxiety, among other information. The study will be ongoing.

Based on the results, the researchers made some recommendations.

Depression & Parkinson's Disease Details

Mood disorders are common among people with Parkinson's, the researchers found. Besides widespread depression, anxiety is common.

"We have become more acutely aware over the last few years that these non-movement factors are impacting people's quality of life," Okun says.

Doctors should screen people with Parkinson's for depression at least once a year, the foundation says. Patients are encouraged to report mood changes to their doctors. Family members are also encouraged to accompany them to doctor’s visits and to discuss any changes in patients’ mood.

Treatment with medications and talk therapy, as well as getting regular exercise, can help, according to the researchers. "People's quality of life can significantly improve," Oberdorf says.

It's important to realize, Oberdorf says, that the depression is part of the disease, a chemical phenomenon. "It's not, 'Oh, I have Parkinson's disease and I'm depressed,'" she says.

The depression, she and others say, is related to changes inherent in the disease, such as a decline in the brain chemical dopamine. It helps control the brain's reward and pleasure centers.

Tracking Parkinson's Disease: Other Findings

Exercising more than 2.5 hours a week is linked with fewer mobility problems and less difficulty in doing everyday activities, according to the researchers.

While all the centers were considered expert at caring for Parkinson's disease patients, the care itself varied, the research found.

There were different referral rates, for instance, to physical, occupational, and other therapists.

Depression & Parkinson's: One Man's Story

Jeff Mackey of Melrose, Fla., is one of the 50% of Parkinson's patients who knows all too well about depression.

The 60-year-old Episcopal priest was diagnosed with Parkinson's disease five years ago, after noticing a hand tremor first thought to be harmless.

He had struggled with mild depression starting in his teen years, he says. It was kept under control, sometimes with low doses of medication, he says.

But when his neurologist diagnosed Parkinson's, he also told Mackey the depression had gotten worse.

Mackey is now on a mood stabilizer and another drug for the depression. "My mood now is much higher; it's stable," he says. "I am able to kind of float above the depression."

Depression still brings him down a day or two a month -- much less than before, he says. "It's gone from almost constant to rare," he says.

Parkinson's Patients' Challenges: Perspectives

The study findings, especially those about depression, ring true with neurologists who treat people with Parkinson's.

"I am not surprised at all by the depression findings," says Michele Tagliati, MD, director of the movement disorders program at Cedars-Sinai Medical Center, Los Angeles. "It's something we see all the time," he says.

"The depression really colors the experience of these patients in a dramatic way," he says. "It's not the sadness of someone looking in the mirror [and saying, 'I have Parkinson's']. It is an integral part of the disease."

Others agree.

"There is a strong link between psychological symptoms and Parkinson's," says William Buxton, MD, medical director of neurodiagnostics at the UCLA Medical Center, Santa Monica, and associate clinical professor of neurology at the UCLA David Geffen School of Medicine.

"Many patients have generalized anxiety for a year or two before symptoms," he says, citing anecdotal and published reports.

The new report, he says, "reinforces what we know, that Parkinson's is not only a disease that just affects walking and motor function, but impacts a patient's sense of well-being and psychological state."

For patients, he says, "the message ... is to stay on top of how they are feeling emotionally" and to keep their doctors informed.